Hi Toots, I think a FBG should be pretty soon after waking. I put my testing kit on the bedside if I particularly want to get a FBG reading. The thing to remember is that the dawn phenomenon (where the liver dumps glucose in the blood stream to get you going of a morning) can distort that reading, also eating something late at night can have an effect on your FBG reading. I don't always bother because there is so much your body does naturally that you have little control over that effects that reading.
If you test pre breakfast that is a legit pre meal fasting reading but could be distorted by tea or coffee that you have drunk since waking. Caffeine in particular can in some people cause BG rises.